- Email: [email protected]
Mass attenuation coefficients of X-rays in different medicinal plants
ARTICLE IN PRESS Applied Radiation and Isotopes 68 (2010) 271–274
Contents lists available at ScienceDirect
Applied Radiation and Isotopes journal homepage: www.elsevier.com/locate/apradiso
Mass attenuation coefficients of X-rays in different medicinal plants R.B. Morabad, B.R. Kerur Department of Post-Graduate Studies and Research in Physics, Gulbarga University, Gulbarga 585106, Karnataka, India
a r t i c l e in fo
abstract
Article history: Received 4 November 2008 Received in revised form 23 March 2009 Accepted 18 October 2009
The mass attenuation coefficients of specific parts of several plants, (fruits, leaves, stem and seeds) often used as medicines in the Indian herbal system, have been measured employing NaI (TI)) detector. The electronic setup used is a NaI (TI) detector, which is coupled to MCA for analysis of the spectrum. A source of 241Am is used to get X-rays in the energy range 8–32 keV from Cu, Rb, Mo, Ag and Ba targets. In the present study, the measured mass attenuation coefficient of Ocimum sanctum, Catharanthus roseus, Trigonella foenum-graecum, Azadirachta indica, Aegle marmelos, Zingiber officinalis, Emblica officinalis, Anacardium occidentale, Momordica charantia and Syzygium cumini show a linear relation with the energy. & 2009 Elsevier Ltd. All rights reserved.
PACS: 25.20.Dc 25.60.Dz 29.30.Kv 29.40. n Keywords: Medicinal plants Mass attenuation coefficients Trace elements
1. Introduction Medicinal plants have been used for many years to cure a great variety of diseases. Recently, according to the World Health Organization, the use of traditional herbal medicine has spread not only in developing countries but also in the Industrialized ones, as a complementary way to treat and to prevent illnesses (WHO, 2003). A great advantage of plants as bioindicaters is that they are stationary, are commonly available in large numbers and generate an interest in medicinal plants that has led to their wide acceptance in medicinal, pharmaceutical and cosmetic industries. The pharmacological properties of medicinal plants have been attributed to the presence of active constituents, which are responsible for important physiological function in living organisms. It has been reported that trace elements play an important role in the reactions, which will lead to the formation of these active constituents (Sefor-Armah et al., 2001). However, a correlation between elemental composition of medicinal plants and their curative properties have not been presented for medicinal plants and are of great importance to understanding their pharmacological actions (Sefor-Armah et al., 2002). Due to the importance of the mineral and trace elements present in medicinal plants, several studies have been carried out
Corresponding author. Tel.: + 918472 246639.
E-mail address: [email protected] (B.R. Kerur). 0969-8043/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2009.10.033
to determine their levels by atomic absorption spectrophotometry (Caldas and Machado, 2004; Ajasa et al., 2004), X-ray fluorescence spectrometry (Obiajunwa et al., 2002; Salvador et al., 2003; Mohanta et al., 2003) and Neutron activation analysis (Naidu et al., 1999; Sefor-Armah et al., 2001). Next, the data on attenuation coefficient measurement in compounds especially in medicinal plants like Catharanthus roseus, Trigonella foenum-graecum, Azadirachta indica, Aegle marmelos, Zingiber officinalis, Emblica officinalis, Anacardium occidentale, Momordica charantia and Syzygium cumin, samples are not found in the literature seems to be very very limited. Some medicinal plants especially C. roseus, Z. officinalis and T. foenumgraecum, have been used for treatments like fever, cancer, diabetes, cough, stomach, jaundice, and hyperacidity. It is therefore worthwhile to undertake a systematic study of photon interaction cross sections in medicinal plant samples. On the basis of the above work, a plan of work has been designed on medicinal plants to study the followings: (1) To study the elemental compositions of the medicinal plants by collecting the sample from the different region of north Karnataka by PIXE method. (2) To study the nature of mass attenuation coefficient of these medicinal plants by the transmission method from this effective atomic number and electron density of sample can be estimated which are needed for the XRF. (3) Study of the influences and these trace elements on the biological activities.
ARTICLE IN PRESS 272
R.B. Morabad, B.R. Kerur / Applied Radiation and Isotopes 68 (2010) 271–274
In the present work, the mass attenuation coefficient of the some parts of medicinal plants considered as an absorber have been measured with great accuracy in view of the determination of effective atomic number and electron density.
2. Theory It is well known that the exponential law determines the narrow beam X-ray mass attenuation coefficient and is expressed as m t ð1Þ I ¼ Io exp
r
where Io and I are the observed intensities without and with the absorber, respectively, t is the mass per unit area of the absorber and mr is the mass attenuation coefficient of target. The mass attenuation can also be expressed as barns per atom through the expression: m ðcm2 =gmÞ sðBarns=atomÞ ¼ ½A=NA 1024 ð2Þ
r
where A is atomic weight of the absorber material and NA is Avogadro’s number. Theoretical values for the mass attenuation coefficient for all element and for some compounds can be found in tabulations, e.g. by Hubbell and Seltzer (1995). By theoretical X-ray mass attenuation coefficients, m/r, for any compound/mixture/material are usually estimated from the sum of weighted contributions from the constituent elements. This is based on the assumption that contributions of each element to the attenuation is additive and the law is known as Braggs additive law or the more commonly called mixture rule which is given by m X m ¼ wi ðcm2 Þ=gm ð3Þ
r
i
r
i
where wi and (m/r)i are the weight fraction and the mass attenuation coefficient, of the ith element, respectively. In a compound, the weight fraction of the ith element is given by aA wi ¼ P i i j aj Aj
ð4Þ
where ai and Ai are, respectively, the number of formula units and the atomic weight of the ith element. The present work deals with measurement of mass attenuation coefficient of X-rays in herbal medicines in the energy range from 8.136 keV to 32.581 keV. Here the C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale, M. charantia and S. cumini are selected as absorbers, all of which are widely used for stomach pains.
Fig. 1. Schematic experimental setup. A: Aluminum Stand, SP: Specimen, C1 & C2: Aluminum Collimators, S: Source and D: NaI(T1) detector.
multiplier tube (PMT) served as X-ray detector. Oxford model PCA P-plus single card performed as PMT power supply, Pre-amplifier, amplifier, 1 K ADC and MCA with control from software package OXWIN MCA. The medicinal plants are collected from different places. The leaves and seeds of these plants are washed with distilled water and air-dried in shade over a period of one month. They are finely grinded with a pestle and mortar. The grinded powder is sieved using a mesh size of 260 mm. The samples of different thicknesses are prepared by weighing a quantity of the finely grinded powder and pressing it to a 10 mm dia cylindrical pellet with an hydraulic press (without a binder). The areal thickness of the pellets was calculated using an electronic weighing balance and a traveling microscope. As established earlier, for a given photon energy, accurate values of attenuation can be obtained by choosing the range of target thickness over 50–2% transmission. The transmitted intensity was obtained by taking the area under the photo peak in the transmitted spectrum. The slope of the linear plot of the logarithm of transmitted intensity versus specimen thickness would yield attenuation coefficient. The standardization of the experimental method has been done for the elemental foils and same is adopted in the present work (Nagabhushan et al., 2004). Since the detector has a poor energy resolution, the energy corresponding to the measured attenuation coefficient is the weighted average of Ka Kb and X-rays energies.
3. Experiment 4. Results and discussions The schematic experimental setup used in the present work is shown in the Fig. 1. The procedure adopted for the determination of the mass attenuation coefficient is described elsewhere (Nagabhushan et al., 2004) and briefly explained here: photons from a variable energy X-ray source passed through a collimator and are incident on the specimen in the form of a thin foil/pellet kept normal to the photon beam. The transmitted beam passes through another collimator and reaches a NaI (Tl) X-ray detector. The transmitted photon spectrum was recorded using a PC based multichannel analyzer. A primary source 241Am is used to get X-rays in the energy range 8 to 32 keV from Cu, Rb, Mo, Ag and Ba targets. A Bicorn makes integrated assembly of 25 mm dia 4 mm thick NaI (TI) scintillator mounted on a photo
In Table 1, the measured mass attenuation coefficient values along with errors for medicinal plant compounds are presented. The error involved in the experimental values is about less than about 2% in each sample. The determined mass attenuation coefficients on O. sanctum, C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale, M. charantia and S. cumini shows that the mixture rule is valid even though the percentage mixture of content is found from the literatures. The samples were collected from the different regions of North Karnataka, from coefficient data it is clear that the variation among values for single sample for each energy is within the 5%, which shows the content in the sample is same irrespective of the
ARTICLE IN PRESS R.B. Morabad, B.R. Kerur / Applied Radiation and Isotopes 68 (2010) 271–274
273
Table 1 Mass attenuation coefficients of X-rays in different medicinal plants from three areas like : Ka—Kappadugadda, Sa—Sandur, Gu—Gulbarga. Energy sample name
8.136 keV
13.596 keV
17.781 keV
22.581 keV
32.891 keV
Ocimum sanctum Ka Sa Gu Mean
18.58 70.19 18.09 70.22 18.32 70.17 18.33 70.14
3.685 70.033 3.539 70.034 3.795 70.032 3.673 70.072
1.736 7 0.018 1.514 7 0.013 1.639 7 0.013 1.629 7 0.06
1.055 7 0.013 0.982 7 0.014 1.077 7 0.021 1.0380 7 0.03
0.3475 7 0.0034 0.3563 7 0.0032 0.3668 7 0.0037 0.3569 7 0.0056
Catharanthus roseus Ka Sa Gu Mean
25.23 70.25 24.95 70.28 25.09 70.19 25.09 70.08
6.778 70.081 6.528 70.073 6.662 70.077 6.656 70.072
4.355 7 0.052 3.986 7 0.045 4.198 7 0.042 4.179 7 0.106
2.297 7 0.032 2.052 7 0.028 2.381 7 0.026 2.243 7 0.098
0.9782 7 0.0231 0.9851 7 0.0197 0.9237 7 0.0214 0.962 7 0.0194
Trigonella foenum-graecum Ka Sa Gu Mean
22.76 70.22 21.12 70.27 22.65 70.25 22.18 70.53
6.188 70.056 6.345 70.065 6.433 70.587 6.322 70.072
4.123 7 0.051 3.987 7 0.043 4.132 7 0.051 4.0807 0.047
2.097 7 0.038 1.998 7 0.041 2.213 7 0.042 2.103 7 0.062
0.7876 7 0.0162 0.7694 7 0.0186 0.7982 7 0.0195 0.785 7 0.00841
Azadirachta indica Ka Sa Gu Mean
23.23 70.31 24.98 70.34 22.28 70.35 23.49 70.79
6.261 70.063 6.433 70.054 6.321 70.055 6.338 70.050
3.995 7 0.041 4.0217 0.054 4.136 7 0.052 4.0507 0.043
1.976 7 0.039 2.012 7 0.041 2.094 7 0.044 2.0273 7 0.04
0.9324 7 0.0182 0.9456 7 0.0132 0.8973 7 0.0207 0.9251 7 0.0144
Aegle marmelos Ka Sa Gu Mean
11.97 70.15 12.32 70.13 11.54 70.16 11.94 70.23
3.434 70.036 3.821 70.038 3.452 70.033 3.569 70.126
1.676 7 0.021 1.876 7 0.025 1.645 7 0.028 1.732 7 0.072
0.8701 7 0.01 0.9653 7 0.01 0.8892 7 0.01 0.9087 0.029
0.4563 7 0.0057 0.5545 7 0.0053 0.4986 7 0.0058 0.503 7 0.0284
Zingiber officinalis Ka Sa Gu Mean
19.54 70.29 19.09 70.28 18.76 70.21 19.13 70.23
5.312 70.058 5.021 70.051 5.398 70.056 5.243 700.114
2.892 7 0.032 2.243 7 0.035 2.567 7 0.028 2.567 7 0.187
1.737 7 0.026 1.255 7 0.027 1.765 7 0.021 1.585 7 0.1655
0.6686 7 0.0071 0.5942 7 0.0084 0.6122 7 0.0076 0.6250 7 0.022
Emblica officinalis Ka Sa Gu Mean
9.34 70.16 10.32 70.13 9.891 70.15 9.850 70.28
2.702 70.0267 2.678 70.0291 2.452 70.0243 2.610 70.0796
1.231 7 0.019 1.113 7 0.017 1.298 7 0.013 1.214 7 0.054
0.5965 7 0.008 0.4983 7 0.002 0.6034 7 0.002 0.566 7 0.0340
0.3351 7 0.0047 0.3402 7 0.0039 0.3391 7 0.0041 0.3381 7 0.002
Anacardium occidentale Ka Sa Gu Mean
10.75 70.16 11.92 70.14 10.52 70.16 11.06 70.43
3.428 70.003 3.743 70.033 3.448 70.032 3.5397 70.102
1.979 7 0.026 2.0237 0.028 1.987 7 0.025 1.996 7 0.014
0.832 7 0.0018 0.872 7 0.0019 0.834 7 0.0016 0.8460 7 0.013
0.328 7 0.0046 0.363 7 0.0043 0.302 7 0.0045 0.3310 7 0.018
20.30 70.25 22.21 70.22 20.89 70.27 21.13370.56
5.395 70.062 5.376 70.058 5.402 70.062 5.391 70.007
3.3507 0.031 3.298 7 0.035 3.387 7 0.033 3.345 7 0.026
1.768 7 0.0032 1.721 7 0.0028 1.692 7 0.0034 1.727 7 0.0221
0.5432 7 0.0059 0.5122 7 0.0061 0.5321 7 0.0057 0.529 7 0.00907
2.597 70.0038 2.654 70.032 2.773 70.028 2.675 70.052
1.536 7 0.016 1.494 7 0.017 1.543 7 0.015 1.524 7 0.015
0.7651 7 0.0096 0.7982 7 0.0093 0.7543 7 0.0098 0.7725 7 0.0132
0.3567 7 0.0048 0.3328 7 0.0051 0.3754 7 0.0044 0.355 7 0.01233
Momordica charantia Ka Sa Gu Mean Syzygium cumini Ka Sa Gu Mean
9.644 70.016 10.02 70.011 9.865 70.013 9.843 70.109
region of collection of the sample. Hence, the presented values of mass attenuation coefficient can be taken as a measure of the composition of elements present in the sample. In the present case, it is a non-destructive method, means the samples are dried, grinded and made prepared the pallets, but in case of other methods the sample is totally destroyed and then analysis can be made. The different region of organic elemental compositions of different region of each sample can be made accuracy of 5% by this method, it is easy and not cost effective compared with other methods. It may be pointed here, that even though the photon interaction is with the individual elements, the mass attenuation coefficient gives information of sample as a whole, which is of beauty of the photon atom interaction. The experimental mean value of mass attenuation coefficients for medicinal plants at five photon energies are presented in
Table 2. Using the chemical analysis method the following different percentage of the protein, fat, carbohydrates, crude fiber, ash, calcium, phosphorus, iron, are found in different medicinal plants. These percentages are then used to calculate the theoretical values of the medicinal plants and are presented after each experimental values of mass attenuation coefficient in Table 2. The over all difference between the experimental and the theoretical value is found to be between 3% and 16%. Here, for the first time it is tried to present the theoretical values of mass attenuation coefficient of medicinal plants, since it difficulty to get the percentage of the elemental compositions of each samples. These values are utilized for plotting the graph. Another interesting point to discuss from Fig. 2 is that; graph of ln(E) against ln(m/r) yields a straight line, showing the variation of the attenuation coefficient with energy. This is linear irrespective of
ARTICLE IN PRESS 274
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Table 2 The mean Mass attenuation coefficients of X-rays in different medicinal plants compared with winxcom values. Sample name
8.136 keV
Ocmium sanctum Catharanthus roseus Trigonella foenum-graecum Azadirachta indicaSKO18N3C12H86 Aegle marmelos Zingiber officinalis Emblica officinalis Anacardium occidentale Momordica charantia Syzygiuim cumini
13.596 keV
17.781 keV
Ln of attenuation coefficient
32.891 keV
Expt.
Theory
Expt.
Theory
Expt.
Theory
Expt.
Theory
Expt.
Theory
18.33 7 0.14 25.09 7 0.08 22.18 7 0.53 23.49 7 0.79 11.94 7 0.23 19.13 7 0.23 9.85 7 0.28 11.06 7 0.43 21.13 7 0.56 9.84 7 0.11
15.87 22.13 19.43 19.88 10.34 17.89 10.82 11.98 18.33 10.67
3.673 7 0.072 6.656 7 0.072 6.322 7 0.072 6.338 7 0.050 3.569 7 0.126 5.243 7 0.114 2.610 7 0.079 3.539 7 0.102 5.391 7 0.007 2.675 7 0.052
3.98 5.85 5.98 5.78 3.89 4.87 2.87 3.43 5.90 2.56
1.629 7 0.06 4.179 7 0.106 4.0807 0.047 4.0507 0.043 1.732 7 0.072 2.567 7 0.187 1.214 7 0.054 1.996 7 0.014 3.345 7 0.026 1.524 7 0.015
1.64 3.98 3.67 4.21 1.78 2.55 1.13 2.04 3.25 1.44
1.0387 0.03 2.243 7 0.098 2.1037 0.062 2.0277 0.042 0.9087 0.029 1.585 7 0.165 0.5667 0.034 0.8467 0.013 1.727 7 0.022 0.7727 0.013
0.98 2.32 2.09 1.89 0.95 1.67 0.59 0.91 1.65 0.72
0.3577 0.005 0.9627 0.019 0.7857 0.008 0.9257 0.014 0.5037 0.028 0.6257 0.022 0.3387 0.002 0.3317 0.018 0.5297 0.009 0.3557 0.012
0.345 0.931 0.801 0.933 0.498 0.618 0.335 0.380 0.541 0.367
Energy Vs Attenuation coefficient Slope 2.79 SD 0.12 R 0.99 N 5 Square - Experimental Circle - Theoretical
7.38906
22.581 keV
2.71828
1
M. charantia and S. cumini) and good recovery values were obtained in all cases. Thus, if any difference is observed between the mass attenuation coefficients of Z. officinalis then our experiment will indicate changes from plants in one area to another. Hence the present author recommends that, this method will satisfies the needs of the biological scientists for the checking the uniformity herbal plants by the transmission method when samples are collected from different regions. Further, it is important to mention here that diversity observed among herbal drugs originating from plants of the same family is attributed to differences in their botanical structures, element mobility within the plant parts and other internal and external sources.
0.36788 Acknowledgment
0.13534 7.38906
20.08554
This work is carried out under BRNS project work sanctioned to BRK.
Ln Energy in keV Fig. 2. Graph of ln(E) against ln(m/r) in cm2/g.
the elements present, provided that the sample dose not contain an element whose k shell binding is not close to the incident photon energy, in which case, the graph would show a deviation from linearity. The value of the exponent from the graph is found to be between n = 2.54 and n =2.39 in all the cases, which agree with the expected value (Evans, 1982) which is dependent on the energy as well as atomic number. Hence the measured value of the mass attenuation coefficient will give at least, in a broad sense, that the sample is uniformly prepared the (m/r) values in the true values at these energies.
5. Conclusion Determination of elements in herbal medicines are important since these are used to treat a variety of diseases and conditions relating to cancer, diabetes control, fever, and stress avoidance, and have promising therapeutic properties. In the present work, the determined attenuation coefficients of O. sanctum, C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale, M. charantia and S. cumini are useful for XRF studies. The complete procedures were validated using a certified reference material (O. sanctum, C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale,
References Ajasa, A.M.O., Bello, M.O., Ibrahim, A.O., Ogunwande, I.A., Olawore, N.O., 2004. Heavy trace metals and macronutrients status in herbal plants of Nigeria. Food Chem. 85, 67–71. Caldas, E.D., Machado, L., 2004. Cadmium, mercury and lead in medicinal herbs in Brazil. Food Chem. Toxicol. 42, 599–603. Evans, R.D., 1982. The Atomic Nucleus, T M H ed New Delhi, pp. 699–710. Hubbell, J.H., Seltzer, S.M., 1995. Tables of X-ray mass attenuation coefficients from keV to 20 MeV for elements Z= 1 to 92 NIST (IR) Report no. 5432. Mohanta, B., Chakraborty, A., Sudarshan, M., Dutta, R.K., Baruah, M., 2003. Elemental profile in some common medicinal plants of India. Its correlation with traditional therapeutic usage. J. Radioanal. Nucl. Chem. 258, 175–179. Naidu, G.R.K., Denschlag, H.O., Mauerhofer, E., Porte, N., Balaji, T., 1999. Determination of macro, micro nutrient and trace elements concentration in Indian medicinal vegetables leave using instrumental neutron activation analysis. Appl. Radiat. Isot. 50, 947–953. Nagabhushan, N.M., Kerur, B.R., Lagare, M.T., Nathuram, R., Abani, M.C., Thontadarya, S.R., Hanumaiah, B., 2004. J. X-ray Sci. Technol. 12, 161. Obiajunwa, E.I., Adebajo, A.C., Omobuwajo, O.R., 2002. Essential and trace element contents of some Nigerian medicinal plants. J. Radioanal. Nucl. Chem. 252 (3), 473–476. Sefor-Armah, Y., Nyarko, B.J.B., Akaho, E.H.K., Kyere, A.W.K., Osae, S., Oppong Boachie, K., Osae, E.K.J., 2001. Activation analysis of some essential elements in five medicinal plants used in Ghana. J. Radioanal. Nucl. Chem. 250 (1), 173–176. Sefor-Armah, Y., Nyarko, B.J.B., Akaho, E.H.K., Kyere, A.W.K., Osae, S., OppongBoachie, K., 2002. Multielemental analysis of some traditional plant medicines used in Ghana. J. Trace Microprobe Technol. 20 (3), 419–427. Salvador, M.J., Dias, D.A., Moreira, S., Zucchi, O.L.A.D., 2003. Analysis of medicinal plants and crude extracts by synchrotron radiation total reflection X-ray flouresence. J. Trace Microprobe Technol. 21 (2), 377–388. WHO–World Health Organization, 2003. Traditional Medicine, Fact sheet no. 134, May. Available at:/www.who.int/mediacentre/factsheets.2003/fs134/enS access in: 07/08/2003.
Contents lists available at ScienceDirect
Applied Radiation and Isotopes journal homepage: www.elsevier.com/locate/apradiso
Mass attenuation coefficients of X-rays in different medicinal plants R.B. Morabad, B.R. Kerur Department of Post-Graduate Studies and Research in Physics, Gulbarga University, Gulbarga 585106, Karnataka, India
a r t i c l e in fo
abstract
Article history: Received 4 November 2008 Received in revised form 23 March 2009 Accepted 18 October 2009
The mass attenuation coefficients of specific parts of several plants, (fruits, leaves, stem and seeds) often used as medicines in the Indian herbal system, have been measured employing NaI (TI)) detector. The electronic setup used is a NaI (TI) detector, which is coupled to MCA for analysis of the spectrum. A source of 241Am is used to get X-rays in the energy range 8–32 keV from Cu, Rb, Mo, Ag and Ba targets. In the present study, the measured mass attenuation coefficient of Ocimum sanctum, Catharanthus roseus, Trigonella foenum-graecum, Azadirachta indica, Aegle marmelos, Zingiber officinalis, Emblica officinalis, Anacardium occidentale, Momordica charantia and Syzygium cumini show a linear relation with the energy. & 2009 Elsevier Ltd. All rights reserved.
PACS: 25.20.Dc 25.60.Dz 29.30.Kv 29.40. n Keywords: Medicinal plants Mass attenuation coefficients Trace elements
1. Introduction Medicinal plants have been used for many years to cure a great variety of diseases. Recently, according to the World Health Organization, the use of traditional herbal medicine has spread not only in developing countries but also in the Industrialized ones, as a complementary way to treat and to prevent illnesses (WHO, 2003). A great advantage of plants as bioindicaters is that they are stationary, are commonly available in large numbers and generate an interest in medicinal plants that has led to their wide acceptance in medicinal, pharmaceutical and cosmetic industries. The pharmacological properties of medicinal plants have been attributed to the presence of active constituents, which are responsible for important physiological function in living organisms. It has been reported that trace elements play an important role in the reactions, which will lead to the formation of these active constituents (Sefor-Armah et al., 2001). However, a correlation between elemental composition of medicinal plants and their curative properties have not been presented for medicinal plants and are of great importance to understanding their pharmacological actions (Sefor-Armah et al., 2002). Due to the importance of the mineral and trace elements present in medicinal plants, several studies have been carried out
Corresponding author. Tel.: + 918472 246639.
E-mail address: [email protected] (B.R. Kerur). 0969-8043/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2009.10.033
to determine their levels by atomic absorption spectrophotometry (Caldas and Machado, 2004; Ajasa et al., 2004), X-ray fluorescence spectrometry (Obiajunwa et al., 2002; Salvador et al., 2003; Mohanta et al., 2003) and Neutron activation analysis (Naidu et al., 1999; Sefor-Armah et al., 2001). Next, the data on attenuation coefficient measurement in compounds especially in medicinal plants like Catharanthus roseus, Trigonella foenum-graecum, Azadirachta indica, Aegle marmelos, Zingiber officinalis, Emblica officinalis, Anacardium occidentale, Momordica charantia and Syzygium cumin, samples are not found in the literature seems to be very very limited. Some medicinal plants especially C. roseus, Z. officinalis and T. foenumgraecum, have been used for treatments like fever, cancer, diabetes, cough, stomach, jaundice, and hyperacidity. It is therefore worthwhile to undertake a systematic study of photon interaction cross sections in medicinal plant samples. On the basis of the above work, a plan of work has been designed on medicinal plants to study the followings: (1) To study the elemental compositions of the medicinal plants by collecting the sample from the different region of north Karnataka by PIXE method. (2) To study the nature of mass attenuation coefficient of these medicinal plants by the transmission method from this effective atomic number and electron density of sample can be estimated which are needed for the XRF. (3) Study of the influences and these trace elements on the biological activities.
ARTICLE IN PRESS 272
R.B. Morabad, B.R. Kerur / Applied Radiation and Isotopes 68 (2010) 271–274
In the present work, the mass attenuation coefficient of the some parts of medicinal plants considered as an absorber have been measured with great accuracy in view of the determination of effective atomic number and electron density.
2. Theory It is well known that the exponential law determines the narrow beam X-ray mass attenuation coefficient and is expressed as m t ð1Þ I ¼ Io exp
r
where Io and I are the observed intensities without and with the absorber, respectively, t is the mass per unit area of the absorber and mr is the mass attenuation coefficient of target. The mass attenuation can also be expressed as barns per atom through the expression: m ðcm2 =gmÞ sðBarns=atomÞ ¼ ½A=NA 1024 ð2Þ
r
where A is atomic weight of the absorber material and NA is Avogadro’s number. Theoretical values for the mass attenuation coefficient for all element and for some compounds can be found in tabulations, e.g. by Hubbell and Seltzer (1995). By theoretical X-ray mass attenuation coefficients, m/r, for any compound/mixture/material are usually estimated from the sum of weighted contributions from the constituent elements. This is based on the assumption that contributions of each element to the attenuation is additive and the law is known as Braggs additive law or the more commonly called mixture rule which is given by m X m ¼ wi ðcm2 Þ=gm ð3Þ
r
i
r
i
where wi and (m/r)i are the weight fraction and the mass attenuation coefficient, of the ith element, respectively. In a compound, the weight fraction of the ith element is given by aA wi ¼ P i i j aj Aj
ð4Þ
where ai and Ai are, respectively, the number of formula units and the atomic weight of the ith element. The present work deals with measurement of mass attenuation coefficient of X-rays in herbal medicines in the energy range from 8.136 keV to 32.581 keV. Here the C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale, M. charantia and S. cumini are selected as absorbers, all of which are widely used for stomach pains.
Fig. 1. Schematic experimental setup. A: Aluminum Stand, SP: Specimen, C1 & C2: Aluminum Collimators, S: Source and D: NaI(T1) detector.
multiplier tube (PMT) served as X-ray detector. Oxford model PCA P-plus single card performed as PMT power supply, Pre-amplifier, amplifier, 1 K ADC and MCA with control from software package OXWIN MCA. The medicinal plants are collected from different places. The leaves and seeds of these plants are washed with distilled water and air-dried in shade over a period of one month. They are finely grinded with a pestle and mortar. The grinded powder is sieved using a mesh size of 260 mm. The samples of different thicknesses are prepared by weighing a quantity of the finely grinded powder and pressing it to a 10 mm dia cylindrical pellet with an hydraulic press (without a binder). The areal thickness of the pellets was calculated using an electronic weighing balance and a traveling microscope. As established earlier, for a given photon energy, accurate values of attenuation can be obtained by choosing the range of target thickness over 50–2% transmission. The transmitted intensity was obtained by taking the area under the photo peak in the transmitted spectrum. The slope of the linear plot of the logarithm of transmitted intensity versus specimen thickness would yield attenuation coefficient. The standardization of the experimental method has been done for the elemental foils and same is adopted in the present work (Nagabhushan et al., 2004). Since the detector has a poor energy resolution, the energy corresponding to the measured attenuation coefficient is the weighted average of Ka Kb and X-rays energies.
3. Experiment 4. Results and discussions The schematic experimental setup used in the present work is shown in the Fig. 1. The procedure adopted for the determination of the mass attenuation coefficient is described elsewhere (Nagabhushan et al., 2004) and briefly explained here: photons from a variable energy X-ray source passed through a collimator and are incident on the specimen in the form of a thin foil/pellet kept normal to the photon beam. The transmitted beam passes through another collimator and reaches a NaI (Tl) X-ray detector. The transmitted photon spectrum was recorded using a PC based multichannel analyzer. A primary source 241Am is used to get X-rays in the energy range 8 to 32 keV from Cu, Rb, Mo, Ag and Ba targets. A Bicorn makes integrated assembly of 25 mm dia 4 mm thick NaI (TI) scintillator mounted on a photo
In Table 1, the measured mass attenuation coefficient values along with errors for medicinal plant compounds are presented. The error involved in the experimental values is about less than about 2% in each sample. The determined mass attenuation coefficients on O. sanctum, C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale, M. charantia and S. cumini shows that the mixture rule is valid even though the percentage mixture of content is found from the literatures. The samples were collected from the different regions of North Karnataka, from coefficient data it is clear that the variation among values for single sample for each energy is within the 5%, which shows the content in the sample is same irrespective of the
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Table 1 Mass attenuation coefficients of X-rays in different medicinal plants from three areas like : Ka—Kappadugadda, Sa—Sandur, Gu—Gulbarga. Energy sample name
8.136 keV
13.596 keV
17.781 keV
22.581 keV
32.891 keV
Ocimum sanctum Ka Sa Gu Mean
18.58 70.19 18.09 70.22 18.32 70.17 18.33 70.14
3.685 70.033 3.539 70.034 3.795 70.032 3.673 70.072
1.736 7 0.018 1.514 7 0.013 1.639 7 0.013 1.629 7 0.06
1.055 7 0.013 0.982 7 0.014 1.077 7 0.021 1.0380 7 0.03
0.3475 7 0.0034 0.3563 7 0.0032 0.3668 7 0.0037 0.3569 7 0.0056
Catharanthus roseus Ka Sa Gu Mean
25.23 70.25 24.95 70.28 25.09 70.19 25.09 70.08
6.778 70.081 6.528 70.073 6.662 70.077 6.656 70.072
4.355 7 0.052 3.986 7 0.045 4.198 7 0.042 4.179 7 0.106
2.297 7 0.032 2.052 7 0.028 2.381 7 0.026 2.243 7 0.098
0.9782 7 0.0231 0.9851 7 0.0197 0.9237 7 0.0214 0.962 7 0.0194
Trigonella foenum-graecum Ka Sa Gu Mean
22.76 70.22 21.12 70.27 22.65 70.25 22.18 70.53
6.188 70.056 6.345 70.065 6.433 70.587 6.322 70.072
4.123 7 0.051 3.987 7 0.043 4.132 7 0.051 4.0807 0.047
2.097 7 0.038 1.998 7 0.041 2.213 7 0.042 2.103 7 0.062
0.7876 7 0.0162 0.7694 7 0.0186 0.7982 7 0.0195 0.785 7 0.00841
Azadirachta indica Ka Sa Gu Mean
23.23 70.31 24.98 70.34 22.28 70.35 23.49 70.79
6.261 70.063 6.433 70.054 6.321 70.055 6.338 70.050
3.995 7 0.041 4.0217 0.054 4.136 7 0.052 4.0507 0.043
1.976 7 0.039 2.012 7 0.041 2.094 7 0.044 2.0273 7 0.04
0.9324 7 0.0182 0.9456 7 0.0132 0.8973 7 0.0207 0.9251 7 0.0144
Aegle marmelos Ka Sa Gu Mean
11.97 70.15 12.32 70.13 11.54 70.16 11.94 70.23
3.434 70.036 3.821 70.038 3.452 70.033 3.569 70.126
1.676 7 0.021 1.876 7 0.025 1.645 7 0.028 1.732 7 0.072
0.8701 7 0.01 0.9653 7 0.01 0.8892 7 0.01 0.9087 0.029
0.4563 7 0.0057 0.5545 7 0.0053 0.4986 7 0.0058 0.503 7 0.0284
Zingiber officinalis Ka Sa Gu Mean
19.54 70.29 19.09 70.28 18.76 70.21 19.13 70.23
5.312 70.058 5.021 70.051 5.398 70.056 5.243 700.114
2.892 7 0.032 2.243 7 0.035 2.567 7 0.028 2.567 7 0.187
1.737 7 0.026 1.255 7 0.027 1.765 7 0.021 1.585 7 0.1655
0.6686 7 0.0071 0.5942 7 0.0084 0.6122 7 0.0076 0.6250 7 0.022
Emblica officinalis Ka Sa Gu Mean
9.34 70.16 10.32 70.13 9.891 70.15 9.850 70.28
2.702 70.0267 2.678 70.0291 2.452 70.0243 2.610 70.0796
1.231 7 0.019 1.113 7 0.017 1.298 7 0.013 1.214 7 0.054
0.5965 7 0.008 0.4983 7 0.002 0.6034 7 0.002 0.566 7 0.0340
0.3351 7 0.0047 0.3402 7 0.0039 0.3391 7 0.0041 0.3381 7 0.002
Anacardium occidentale Ka Sa Gu Mean
10.75 70.16 11.92 70.14 10.52 70.16 11.06 70.43
3.428 70.003 3.743 70.033 3.448 70.032 3.5397 70.102
1.979 7 0.026 2.0237 0.028 1.987 7 0.025 1.996 7 0.014
0.832 7 0.0018 0.872 7 0.0019 0.834 7 0.0016 0.8460 7 0.013
0.328 7 0.0046 0.363 7 0.0043 0.302 7 0.0045 0.3310 7 0.018
20.30 70.25 22.21 70.22 20.89 70.27 21.13370.56
5.395 70.062 5.376 70.058 5.402 70.062 5.391 70.007
3.3507 0.031 3.298 7 0.035 3.387 7 0.033 3.345 7 0.026
1.768 7 0.0032 1.721 7 0.0028 1.692 7 0.0034 1.727 7 0.0221
0.5432 7 0.0059 0.5122 7 0.0061 0.5321 7 0.0057 0.529 7 0.00907
2.597 70.0038 2.654 70.032 2.773 70.028 2.675 70.052
1.536 7 0.016 1.494 7 0.017 1.543 7 0.015 1.524 7 0.015
0.7651 7 0.0096 0.7982 7 0.0093 0.7543 7 0.0098 0.7725 7 0.0132
0.3567 7 0.0048 0.3328 7 0.0051 0.3754 7 0.0044 0.355 7 0.01233
Momordica charantia Ka Sa Gu Mean Syzygium cumini Ka Sa Gu Mean
9.644 70.016 10.02 70.011 9.865 70.013 9.843 70.109
region of collection of the sample. Hence, the presented values of mass attenuation coefficient can be taken as a measure of the composition of elements present in the sample. In the present case, it is a non-destructive method, means the samples are dried, grinded and made prepared the pallets, but in case of other methods the sample is totally destroyed and then analysis can be made. The different region of organic elemental compositions of different region of each sample can be made accuracy of 5% by this method, it is easy and not cost effective compared with other methods. It may be pointed here, that even though the photon interaction is with the individual elements, the mass attenuation coefficient gives information of sample as a whole, which is of beauty of the photon atom interaction. The experimental mean value of mass attenuation coefficients for medicinal plants at five photon energies are presented in
Table 2. Using the chemical analysis method the following different percentage of the protein, fat, carbohydrates, crude fiber, ash, calcium, phosphorus, iron, are found in different medicinal plants. These percentages are then used to calculate the theoretical values of the medicinal plants and are presented after each experimental values of mass attenuation coefficient in Table 2. The over all difference between the experimental and the theoretical value is found to be between 3% and 16%. Here, for the first time it is tried to present the theoretical values of mass attenuation coefficient of medicinal plants, since it difficulty to get the percentage of the elemental compositions of each samples. These values are utilized for plotting the graph. Another interesting point to discuss from Fig. 2 is that; graph of ln(E) against ln(m/r) yields a straight line, showing the variation of the attenuation coefficient with energy. This is linear irrespective of
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Table 2 The mean Mass attenuation coefficients of X-rays in different medicinal plants compared with winxcom values. Sample name
8.136 keV
Ocmium sanctum Catharanthus roseus Trigonella foenum-graecum Azadirachta indicaSKO18N3C12H86 Aegle marmelos Zingiber officinalis Emblica officinalis Anacardium occidentale Momordica charantia Syzygiuim cumini
13.596 keV
17.781 keV
Ln of attenuation coefficient
32.891 keV
Expt.
Theory
Expt.
Theory
Expt.
Theory
Expt.
Theory
Expt.
Theory
18.33 7 0.14 25.09 7 0.08 22.18 7 0.53 23.49 7 0.79 11.94 7 0.23 19.13 7 0.23 9.85 7 0.28 11.06 7 0.43 21.13 7 0.56 9.84 7 0.11
15.87 22.13 19.43 19.88 10.34 17.89 10.82 11.98 18.33 10.67
3.673 7 0.072 6.656 7 0.072 6.322 7 0.072 6.338 7 0.050 3.569 7 0.126 5.243 7 0.114 2.610 7 0.079 3.539 7 0.102 5.391 7 0.007 2.675 7 0.052
3.98 5.85 5.98 5.78 3.89 4.87 2.87 3.43 5.90 2.56
1.629 7 0.06 4.179 7 0.106 4.0807 0.047 4.0507 0.043 1.732 7 0.072 2.567 7 0.187 1.214 7 0.054 1.996 7 0.014 3.345 7 0.026 1.524 7 0.015
1.64 3.98 3.67 4.21 1.78 2.55 1.13 2.04 3.25 1.44
1.0387 0.03 2.243 7 0.098 2.1037 0.062 2.0277 0.042 0.9087 0.029 1.585 7 0.165 0.5667 0.034 0.8467 0.013 1.727 7 0.022 0.7727 0.013
0.98 2.32 2.09 1.89 0.95 1.67 0.59 0.91 1.65 0.72
0.3577 0.005 0.9627 0.019 0.7857 0.008 0.9257 0.014 0.5037 0.028 0.6257 0.022 0.3387 0.002 0.3317 0.018 0.5297 0.009 0.3557 0.012
0.345 0.931 0.801 0.933 0.498 0.618 0.335 0.380 0.541 0.367
Energy Vs Attenuation coefficient Slope 2.79 SD 0.12 R 0.99 N 5 Square - Experimental Circle - Theoretical
7.38906
22.581 keV
2.71828
1
M. charantia and S. cumini) and good recovery values were obtained in all cases. Thus, if any difference is observed between the mass attenuation coefficients of Z. officinalis then our experiment will indicate changes from plants in one area to another. Hence the present author recommends that, this method will satisfies the needs of the biological scientists for the checking the uniformity herbal plants by the transmission method when samples are collected from different regions. Further, it is important to mention here that diversity observed among herbal drugs originating from plants of the same family is attributed to differences in their botanical structures, element mobility within the plant parts and other internal and external sources.
0.36788 Acknowledgment
0.13534 7.38906
20.08554
This work is carried out under BRNS project work sanctioned to BRK.
Ln Energy in keV Fig. 2. Graph of ln(E) against ln(m/r) in cm2/g.
the elements present, provided that the sample dose not contain an element whose k shell binding is not close to the incident photon energy, in which case, the graph would show a deviation from linearity. The value of the exponent from the graph is found to be between n = 2.54 and n =2.39 in all the cases, which agree with the expected value (Evans, 1982) which is dependent on the energy as well as atomic number. Hence the measured value of the mass attenuation coefficient will give at least, in a broad sense, that the sample is uniformly prepared the (m/r) values in the true values at these energies.
5. Conclusion Determination of elements in herbal medicines are important since these are used to treat a variety of diseases and conditions relating to cancer, diabetes control, fever, and stress avoidance, and have promising therapeutic properties. In the present work, the determined attenuation coefficients of O. sanctum, C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale, M. charantia and S. cumini are useful for XRF studies. The complete procedures were validated using a certified reference material (O. sanctum, C. roseus, T. foenum-graecum, A. indica, A. marmelos, Z. officinalis, E. officinalis, A. occidentale,
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